Among the types of thermoplastics which incorporate a plurality of cyclic structures is the class known as polyarylate polymers. the polyarylates are typically esters of aromatic diacids and dihydric phenols. In such polymers, when 1,6 di(4-hydroxyphenyl)-substituted 1,6-diaza [4.4] spirodilactams are employed as the phenolic component, high molecular weight polymers are difficult to prepare because the reaction medium tends to form an emulsion from which it is difficult to separate and recover the polymer. In U.S. Pat. No. 4,829,144 on preparing polyarylates of spirobiindane bisphenols, it is disclosed that the presence of alcohols in the reaction medium are not suitable because they will preferentially react with the dicarboxylic acid halide. However, Applicant has found that such a preferential reaction does not occur in preparing polyarylates of the [4.4] spirodilactams and that the presence of a deemulsifying agent, such as an alcohol, prevents or breaks emulsions.